Beam compass



G. F. ZUMBUHL 2,419,752

BEAM COMPASS Filed July 31. 1944 My 2 H5 1 mm 2% r D MM my T w 6 April29, 1947.

Patented Apr. 29, 1947 UNID STATES PATENT OFFICE 1 Claim.

The present invention relates to-improvements in a beam compass, and itconsists of the combinations, constructions and arrangements hereinafterdescribed and claimed.

An object of my invention is to provide a beam compass in which the baris formed of two hinged members thus permitting the bar to be foldedinto a compact size when not used.

A further object of my invention is to provide a novel center point andan inscribing member for the beam compass, both of these beingadjustable along the bar into the desired positions. The bodies of thecenter point and the inscribing member are preferably made of atransparent material such as plastic and therefore do not hide the scalemarkings on the bar.

A further object of my invention is to provide a device of the typedescribed in which the center point and the inscribing member have novelclamping means for securing the members to the beam at the desiredplaces.

Other objects and advantages will appear in the following specification,and the novel features of the device will be particularly pointed out inthe appended claim.

My invention is illustrated in the accompanying drawing forming a partof this application, in which:

Figure 1 is a side view of the beam showing the center point andinscribing member partially in section;

Figure 2 is a side elevation of a portion of the clamping means; and

Figure 3 is a transverse section taken along the line 3-3 of Figure 1.

While I have shown only the preferred form of my invention, it should beunderstood that various changes or modifications may be made within thescope of the appended claim without departing from the spirit and scopeof the invention.

In carrying out my invention I provide a bar indicated generally at Aand this bar may be of any length desired. I have shown it as having alength of twenty four inches with a pivot point I at the twelve inchmark so that the two arms 2 and 3 of the bar may be swung about thepivot into alignment with each other as shown in Figure 1 or intooverlapping relation when the device is not used. The pivoted bar ispreferably made of metal and is relatively thin, as shown in Figure 3. Ihave used a Lufkin rule for the bar and the arms 2 and 3 of the rulehave stops 4 that abut each other when the two 2 arms are opened intothe position shown in Figure 1.

On the beam or bar I adjustabl mount a center point, indicated generallyat B; and an inscribing member, indicated generally at 0.

Both the devices 3- and C are identical in construction, except-that thecenter point B carries a pointed steel pin 5 while .the inscribingmember carries a pencil or a soapstone 6. I will describe the member Bin detail and this will sufiice for both the members B and C exceptWhere the member C differs slightly from the structure of the member 3.

A body 1, preferably transparent and hollow, has slots 8 for slidablyreceiving the beam A. I have shown the body 1 bullet-shaped, although Ido not Wish to be confined to this particular design. The pointed end 9of the body l carries the pin 5 and the opposite end has a metal sleevewith a threaded [bore 90.. There are two slots 8 in the body and thelength of the slots is equivalent to the height of the beam.

A clamping cap I!) or sleeve is slidably mounted on the outer surface ofthe body 1. The cap is preferably made of transparent material and.carries a centrally disposed screw I! that is designed to be threadedinto the bore 9. The head of the screw is embedded in the cap. Figure 2shows the cap I 0 provided with an enlarged knurled portion I2 and arounded head I3 at the end of the cap. The cap rim M is designed toengage frictionally with the edge l5 of the rule or beam when the cap isscrewed down into place. The cap can be rotated manually by gripping theknurled portion l2. The cap rim binds the body I to the beam.

The body 1 is transparent and a marker l6, such as an arrow is placed onthe body and is in line with the point 5 so that when the marker isbrought into registry with the desired mark on the scale ii, theoperator will know that the point 5 is in line with the mark. The centerpoint B may be adjusted along the arm 2 and then clamped in position. Itis obvious that the center point B may be placed on the arm 3 ifdesired.

The inscribing member is constructed in identically the same manner asthe member B except that the body 1 has a bore 18 for receiving thepencil 6 or a piece of soapstone. Any marking member may be placed inthe bore 58. The inscribing member will have its similar parts providedwith like reference numerals and a further description of it need not begiven. The member C may be moved along the arm 3 of the beam A or it maybe moved along the arm 2. The inscribing member is clamped in positionby rotating the cap It].

From the foregoing description of the various parts of the device, theoperation thereof may be readily understood.

If a large circle is to be inscribed, the member B is placed on one armand the member C placed on the other. The scale H on the beam permitsthe operator to adjust the distance between the point 5 and the pencil 6to equal the desired radius. The beam pivot point I will not interferewith the use of the beam because the members B and C can be moved closerto the pivot point I if desired or both members may be placed on eitherarm. It is also possible to swing the arm 3 into a right angle positionwith respect members B and C are both placed on the arm 2 and in thisway the arm 3 can act as a handle for moving the inscribing instrumentabout the center point.

It is also possible to use the device as a caliper because when the arms2 and -3 are swung into an angular position with respect to each other,the point 5 and the point of the pencil 6 may be used to contact thepiece being measured and then the distance between the two points 5 and6 may be determined after the instrument is removed from the measuredpiece. The device is extremely simple in construction and is durable andeflicient for the purpose intended.

I claim:

In a device of the type described, a transparent hollow cylindrical bodyhaving longitudinally extending slots in the cylindrical wall forreceiving a bar with a scale thereon, said body having a point at oneend and a threaded =bore at the other, a cap slidable on the body andhaving a screw adapted to enter the threaded bore, whereby a turning ofthe cap will cause the screw to move the cap rim into clampingengagement with the bar.

GOTTFRIED F. ZUMBUHL.

REFERENCES CITED The following references are of record file of thispatent:

UNITED STATES PATENTS in the

